A toner cartridge can be detachably mounted into a main part of an image forming apparatus, and the cartridge, as a whole unit, comprises an electrophotographic photosensitive member and at least one of processing means such as charging means, developing means, cleaning means, or the like. Since the toner cartridge is detachably mountable relative to the main part of the apparatus, it is easy to maintain the apparatus. An electrophotographic image forming apparatus adopting electrophotographic imaging formation method functions as follows: an electrostatic latent image is formed by selectively exposing the electrophotographic photosensitive member uniformly charged by a charger to light passing through the image forming apparatus; the electrostatic latent image is developed with toner by a developing means into a toner image; and the toner image thus formed is transferred onto a recording medium by a transferring means to form an image on the recording material.
As shown in FIG. 1, the prior art has disclosed a method of transmitting the driving force between a photosensitive drum driving head 17 provided on the toner cartridge and an image forming apparatus driving head 18. A spiral triangular recess 18a is provided at an end of the image forming apparatus driving head 18, and a spiral triangular projection 17a is provided correspondingly at an end of the photosensitive drum driving head 17 in complementary with the triangular recess 18a for transmission. The driving force can be transmitted in this manner, however, during transmission of the driving force, the coaxial alignment of the rotation centers of the spiral triangular projection 17a and the spiral triangular recess 18a is difficult, thus leading to a certain shake during the power transmission between them. And the process of manufacturing such a spiral triangular projection 17a is complicated, the cost of making mould is high, and the photosensitive drum driving head 17 is easy to deform or to be damaged during long time operation, which will affect the driving accuracy and efficiency.